1. Field of the Invention
The present invention relates to suppression of color aliasing caused by pixel interpolation.
2. Description of the Background Art
An imaging device such as CCD or CMOS used in a digital camera or the like photoelectrically transfers light received through a color filter to output a pixel signal. Such color filter includes an RGB color filter, a YMCK color filter and the like. A single-chip imaging device outputs a single-color pixel signal per pixel. For instance, when employing the RGB color filter, a pixel signal having one of R (red), G (green) and B (blue) color components is output per pixel.
Therefore, a pixel signal output from a single-chip color imaging device needs to be interpolated with pixel signals of other color components. Various algorithms are used in such interpolation. An exemplary method is to calculate a correlation in the horizontal direction and a correlation in the vertical direction to execute pixel interpolation using pixels present in either direction having a higher correlation. An alternative method is to execute pixel interpolation after assigning weights according to the distance between a target pixel and its neighboring pixels.
Further, Japanese Patent Application Laid-Open No. 2002-300590 describes generating color-difference signals by two different methods after execution of pixel interpolation, and selecting either of the color-difference signals based on chroma values of the respective color-difference signals.
To prevent color aliasing from occurring, various algorithms for executing pixel interpolation have been proposed, however, color aliasing cannot completely be eliminated. The above-mentioned JP2002-300590 describes generating color-difference signals by different methods and selecting either of the color-difference signals based on chroma values, which therefore produces a certain effect of reducing color aliasing, however, a color aliasing component created in the process of generating the selected signal is not suppressed.